1. Technical Field
The disclosure relates to a depth image acquiring device, system, and a method thereof.
2. Related Art
Conventional image sensors are sophisticatedly developed, but with which only two-dimensional information can be acquired, so how to effectively, and stably acquire information of the third dimension (that is, depth) in real time is always a topic in technology development. A depth image can provide more complete spatial image information, and thus can be designed as an operation interface of 3D games or an interactive browsing device. In addition, the depth image also has a great development potential in application in safety image monitoring, robot vision, and medical imaging. At the end of 2010, Microsoft Corporation officially releases a new generation of smart sensory game device Kinect using human actions as an interactive medium of games, in which a depth sensor is a main core element. It can be expected that technology and application thereof related to gesture and human interactive interface will arouse great interest in a next year.
Although a passive image comparison method in the prior art also can calculate a depth image, the passive image comparison method is very liable to influence of the changes in color and brightness of the image due to the high dependence on feature information of the image per se. In case that the image feature is not obvious (for example, blocks of the same color or a white wall), or the ambient brightness is varied (for example, too dark or too bright), a poor comparison result is generally caused, and thus the stability is greatly compromised. Another depth sensing technology is the so-called Time of Flight (TOF) technology, but which suffers from insufficient resolution (160×120-320×240) and limited response rate at present.
An image matching method is disclosed in a document. In the method, matching operations of square difference and sum-of-square-difference (SSD) are directly performed with a dual-image acquired by using stereo vision, and accelerated by GPU. In addition, image features are also created by projecting color codes by using an active light source, and then a match acceleration operation is performed by a pyramid algorithm.
Furthermore, it is disclosed in a document that a gray code pattern is projected, and a sequence of stereo image pairs are acquired by using two cameras, so as to decode spatial locations thereof.
In addition, it is proposed in a document that a main spot pattern is projected, then multiple reference images acquired at different distances are established, and an image correlation calculation for a measured image and the reference patterns is performed, to obtain a distance of the object. In the method, one projecting device and one image acquiring device are used.
It is disclosed in another document that only 1 reference image is established, then correlation calculation for an acquired image of an object and the reference image is performed, and a depth value is obtained according to an offset of a location of a region corresponding to a highest correlation.
A document discloses a system and a method for acquiring a three-dimensional image of a scene. The system includes a projecting device which projects a locally unique pattern to a scene, and multiple sensors for acquiring images of the scenario from two or more observation points. Matching calculation of corresponding pixels in the images is performed, to establish a depth pattern.
A document discloses a device for generating depth information, which includes a projector and a left and a right video cameras. The projector projects a predefined structured light pattern to an object, and each of the left and right video cameras acquires a structured light image, corresponding points of the two images and the projected pattern are determined through decoding calculation of structured light, to obtain depth information. When the structured light pattern cannot be applied with the images, stereo matching of the left and right images is performed, to calculate the depth information.